Variable condenser



Nov. 6, 1928.

, 1,690,095 M. H. BENNETT VARIABLE CONDENSER I Filed'Dec. l, 1926 Patented Nov. 6, 19 28;

UNITED STATES PATENT omen.

MORRIS H. BENNETTyOF WA TERBURY, CONNECTICUT, ASSIGNOR TO SCdVILL MANU- FACTURING COMPANY, OF WATERBURY, CONNECTICUT, A CORPORATION OF CON- NECTICUT.

Application filed December This invention relates to improvements in variable condensers and more particularly to condensers used in radio receiving sets.

One object of this invention is to provide'a variable condenser which when assembled-in a radio receiving set will produce most effi-' cient-results.

In circuits used where several stages or steps of amplification to are employed, each of which is tuned, itiis dificult during'manufacture to maintain the relation oirwires, parts, etc, to such accuracy as to have each circuit of the same distributed capacity. J A

' ltis afeature of this invention to provide improved means for adjusting the capacity of these circuits to the same value, the construction being such that no additional loss will be introduced into the radio frequency circuit. To this end, there is provided an auxiliary condenser plate which is mounted on the frame in the bushing which is usually provided for the terminal connection of the rotor plates.

For a full understanding of the-invention a detailed descriptionof a construction em bodying the same in its most advantageous form will now be given in connection with the accompanying drawings forming a part of this invention and the features forming the invention will then be pointed out inthe appended claims.

In the drawings- Figure 1 is a rear view of a variable con denser embodying the invention;

Figure 2 is a top plan view thereof; and Figure 3 is a section taken along the line 3-3 of Fig. 2. 7

Referring specifically to the drawings, there is shown, for purposes of illustration, avariable condenser comprising a front side 1 and a rear side 2 secured in spaced relation to each other by standards-3. To obtain the advantage ol' interchangeability these standstandards and sides together to form a frame.

in 'radio receiving sets ards 3 are similar in construction and have fiat surfaces to provide alarger bearing face and to be better adapted to support insulat,

" WAItiABLE connnnsnn.

1, i926. Serial No 151,864.

ide 1 has a suitably located opening 5 of such size-that the handle end 6 of rotor shaft 7-, whichmay be of insulating material, may

be positioned in said opening.

A plate 8 having an opening of such size I that it closely fits over end 6 of shaft 7 covers any excess of opening in side 1 and be secured in said side by screws threaded into posts 9, hereinafter referred to. The plate 8 also constitutes a support for the end 6 of shaft- 7. This plate- 8 is so shaped that it does not project beyond the edges of side 1. Side 1 is also provided'with a plurality of perforations to receive studs 10 threaded to receive screws for securing the condenser to the usual panel board to which such condensers are attached,'eithe'r in vertical or horizontal position. The rear ends of these studs are turned down securely against side 1. Plate 12 is secured to the inner 'side of side 1, in any suitablemanner as by posts 9, the inner ends of which posts are turned down to take against plate 12, their outer ends being secured by screws passing through such posts and also through cover plate 8. Plate 12 is also provided with a flanged opening of such size that it allows shaft 7 with its sleeve 11, after the plates 1? have been secured thereon, to pass through, the flange thereof conforming, in shape and size, substantially to that press against the cone endot the sleeve 11,

preventlng play in the rotor while allowing the latter to turn smbothly.

Sleeve 11 carries a set of rotor plates 13 each rotatable between two plates of a set of stator plates 14L, rigidly fixed in blocks 15, 16.

Shaft is provided with a suitable bearing 17 which is preferably adjustable in side 2 as shown.

A terminal binding post 18, threaded to receive the usual securing nuts, is provided on blocks 4; and 41 tor the stator plates. Connection is made from the sleeve 11, holding the rotor plates, by means of a pigtail 19 to a metallic bushing 20 having an internal bore 26, said bushing extending through an opening in the rear side 2, and being supported by suitable insulating'washers 22, 23.

.Preferably the capacity adjustment co'mprises a metallic disk 24 which may, if de-' sired, be provided with a covering of dielecboss 25 causes disk 24 to approach bushing 20.

" v the condenser.

Reverse movement of disk 24 is effected by turning screw 26 in the opposite direction. A spring ,28 maintains the parts in proper relation. Rotation of disk 24 is prevented by splining boss 25 and the walls of bore 26,

as shown at 29 and 30. 'The contact plate 31,

having an upturned finger. 32 for receiving the usual connecting wire, surrounds and con tacts with bushing 20, being held in place by a lock washer 33.-

After the condenser has been assembled'and mounted in an amplifyin circuitot a radio set, adjustment of the zero value of the condensermay bemade by tuning the circuit to receive a'signal at or near the zero capacity of The rotor plates are" then in their zero position. Auxiliary plate '24 is now moved toward or away from outermost stator plate 34 by simplyturning screw -27 out of or into boss 25 until the vdlume of signal received is a maximum.

When one or more condensers are connected I in amplifying circuits in a radio set, the latter be provided a radio set having balanced capacity in all its circuits.

By utilizing the same insulation that is needed to hold the supportingbushing for the pigtail connector to the rotor plates'it is evident that no additional loss will be introduced into the circuit by this construction.

What is claimed is: o

1. A condenser comprising a set of stator plates, a set of rotor plates, an insulated terminal connection .for said rotor plates, an auxiliary element mounted on said connection, means to adjust said element initially with respect to one of said stator plates, and

meansto hold said element in adjusted position.

2. A condenser comprising a frame, a set of stator plates, a set of rotor plates, a bushing constituting an insulated terminal on said frame and connected to said set of rotor plates, an auxiliary element carried in said bushing and adjustable with respect to one of said stator platesi and a spring for holding said element in adjusted position.

-3. In a condenser, and in combination, a

set of stator plates, a set of rotor plates, said plates being mounted to interleave so that said bushing, a terminal connector carried by said bushing, an auxiliary plate carried by said bushing and parallel to one of said stator plates, screw means to adjust said plate with respect to said stator plate, and means for holding said plate in adjusted position.

4. In a condenser, and in combination, a set of stator plates, a set of rotor plates, said plates being mounted to interleave so that the stator plates are outside, a bushing, a flexible 'connectinglead from said rotor platesto said bushing, a terminal connector carried by said bushing, an auxiliary plate having a central.

boss, a bore in said boss threaded to receive an adjusting screw, said bushing being centrally bored to receive said boss, splines on said boss to prevent rotation thereof, and a spring acting upon said boss.

In testimony whereof, I have hereunto set my hand.

Y MORRIS H. BENNETT. 

